of chicago



Sept. 6, 1932- SQLA I 1,875,358

ELECTRIC TRANSFORIBR OriginalFiled larch 1', 1930 Patented Sept. 6, 1932 UNITED ST T S PATENT OFFICE JOSEPH G. SOLA, O l CHICAGO, ILLINOIS, ASSIGNOR 'IOSOLA CORPORATICN, OF, CHICAGO,

, ILLINOIS, A CORPORATION OF ILLINOIS ELECTRIC rmsronm Application fled larch 1, 1830, Zll'o. 488,888. Renewed December 21, 1881.

This invention relates to an electric transformer, and an ob'ect is the provision of a transformerprovi ed with an automaticall operative protection relay ada ted to brea I the circuit of the primary win ing when the load on the secondary winding has been reduced to a predetermined value. More spe- 'cifically, an object of the invention is the provision of an improved type of transformer \30 provided with primary and secondary windmgs, and having an auxiliary secondary winding adapted when connected with a controlling coil of a circuit breaker interposed in the primary coil circuit to cause such cirouit breaker to open. the circuit through the primary coil when the secondary coil circuit is-opened or the load thereon is out down to a predetermined point, but arranged -so that v when there is a normal load on the secondary so coil circuit said circuit breaker shall fail to break such primary coil circuit. It is one, of my objects to provide an arrangement of this type in which the'controlling coil of the a circuit breaker exerts a pullon an armature of the circuit breaker for opening the primary coil circuit, with the arrangement such that when the load on the secondary coil circuit is normal the controlling coil is unable to operate the circuit breaker but that when the load is'cut down to a predetermined minimum or when the secondary coil circuit is opened the pull on the armature becomes sufficiently strong for causing the circuit breaker to operate.

It is one of the objects of my invention to provide an arrangement of this type 'c,omprising means for limiting the magnitude of the current through said two secondary coils so as to insure that there shall be the desired differential strength of pull by said controlling coil for attaining the desired results as above explained. I y I Other objects will appear hereinafter. v The invention consists in the combinations and arrangements of parts hereinafter described and claimed. a a

The invention will be best understood by reference to the accompanying drawing forming a part of this specification, and in 0 which: v

Fig. 1 is a diagrammatic illustration of the parts and devices employed, including the1 transformer and the respective windings; an

Fig. 2 is anend elevational view of the u transformer proper.

As illustrated, the preferred embodiment of the invention comprises a transformer in the form of a rectangular core frame, preferably laminated in structure, and having two 00 parallel lateral yoke portions 4 and 5, with connectingparallel end portions 6 and 7. Extending substantially midway between portions 4 and is a winding core 8 comprising a primary core limb-9 and a secondary 60 core limb 10. Extending laterally from the winding core 8, transversely of the core and in adirection toward the yoke portions 4 and. 5, res ectively, Eare two shunt arms 11- and 12. l y reference to Fig. 1 it will be 10 noted that shunt arms 11 and 12 do not ter- 'minate in contact with the yoke portions 4 and 5, respectively, but are spaced a slight distance therefrom to provide ga s.

In the present embodiment o the inven- 76 tion. the primary and secondary windings are in longitudinal alignment. Primary input wires 13 and 14 are connected to a primary winding 15 on the core part 9, and a secondary winding 16 on the core part 10 is 80 connected to output wires 17 and 18, Connected in the lead 14 so as to be in the primary circuit exteriorly of the transformer, is a circuit breaker 19 having an armature 20 adaptedto be actuated by a controlling coil 86 21 when the latter receives a sufficient supply of current. It will be noted that coil 21 is not connected with either the primary circuitor the secondary circuit, but isconnected by wires 22 and 23 to an auxiliary winding 24 composed of a few turns of relatively heavy wire on the core limb 10 adjacent the yoke end portion 7.

In operation, with the normal load connected across the terminals of the secondary coil 16, the flux set up in the core limb 9 by the current through the primary coil 15 15 divided, part of such flux flowing'through the core limb 10 and threading the secondary coil 16 and the remaining portion being d1- 10.

verted from the core portion to the shunt arms 11 and 12 and across the air gaps at the ends of said shunt arms, the strength of flux required through the core leg 8 for forcing a substantial proportion of such flux to pass through the shunt arms and across the air gaps depending on the size of the air gaps. As the air gaps are narrowed, the maximum limitation with respect to the current which will flow through the coils is correspondingly lowered, a reduction in the size of the air gaps serving to cut down the reluctance of the shunt return path through the arms 11 and 12 for the flow of the magnetic flux therethrough without threading the secondary coils 16 and 24. As such flux is diverted from i the secondary coils, the strength of the current through such secondary coils is correspondingly lowered, and such lowering of the current flowing through the secondary coils acts as a limitation with respect to the flow of current through the primary coil. By regulating the size of the air gaps, accordingly, I am able arbitrarily to limit the strength of current handled by the transformer.

With such current limiting means in use, I am enabled to make thecoil 24 of comparatively heavy wire and of a comparatively small number of turns without danger of undue heating, arranged so that when the circuit is closed through the secondary coil 16, with a portion of the flux flowing through the shunt arms 11 and 12, the current through the coil 24 is very small so as to produce only a slight pull on the armature 20 by the coil 21. The arrangement is such, however, that when the secondary coil circuit is opened so as to cause the counter magnetic flux pressure established by the current through such coil to be eliminated substantially the entire flux flowing through the core leg 9 flows also through the core leg 10 without any substantial diversion of flux through the shunt arms 11 and 12, causing an increase in the current through the coil 24 sufliciently for enabling the coil 21 to operate the circuit breaker for opening the primary circuit through the coil 15.

While I have illustrated and described the preferred form of construction for carrying my invention into efi'ect, this is capable of variation and'modification without departing from the spirit of the invention. I, therefore, do not wish to be limited to the precise details of construction set forth, but desire to avail myself of such variations and modifications as come within the scope of the appended claims.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is 1. In an arrangement of the type described, the combination of core means, a primary coil and a secondary coil in transformer relationship to each other on said core means, an auxiliary coil on said core means, shunt core means including an air-gap located between said primary and said secondary coils adapted when the secondary coil circuit is opened to cause a variation in the strength of the flux threading said auxiliary coil, and means in operative relation with said auxiliary coil adapted automatically to open said primary coil circuit by reason of the change in the strength of the current through said auxiliary coil when said secondary coil circuit is opened.

2. In an arrangement of the type described, the combination of core means comprising a rectangular yoke portion, a transverse core member extending between. two sides of said yoke portion, a primary winding on said transverse core member at one end portion thereof, a secondary winding and an auxiliary winding on said transverse core member in end to end relation to said primary winding, a circuit breaker connected with the primary winding circuit, an operative connection between said circuit breaker and said auxiliary winding, and a magnetic flux shunt arm including an air gap extending laterally from said core member between said primary and secondary windings.

3. In an arrangement of the type described, the combination of core means comprising a rectangular yoke portion, a transverse core member extending between two sides of said yoke portion, a primary winding on said transverse core member at one end portion thereof, a secondary winding and an auxiliary winding on said transverse,core member in end to end relation to said primary winding, a circuit breaker connected with the primary winding circuit, an actuating coil on saidcircuit breaker connected to said aux-' iliary winding, and a magnetic flux shunt arm including an air gap extending laterally from said core member between said primary and secondary windings.

4. In an arrangement of the type described, the combination of core means, a primary coil and a secondary coil in transformer relationship to each other on said core means, an auxiliary coil on said core means, means adapted through the action of the counter magnetic flux pressure set up by the secondary current when the secondary -boil circuit is closed to divert from said auxiliary coil 8. portion of the flux set up by the current through said primary coil and arranged so that when the secondary coil circuit is opened said flux is caused to thread said auxiliary coil, and means adapted automatically to open said primary coil circuit by the action of the increased current through said auxiliary coil when said secondary coil circuit is opened.

5. In anarrangement of the type described, the combination of core means comprising a core bar, return path means connecting the l the current through the primary coilis diverted from said auxiliary coil and arranged so that when the secondary coil circuit is opened said flux is caused to thread said auxsecondary coil and an auxiliary cpil in end to end relation with said primary coiland on the same core bar with sand primary c011 but at the opposite side of said core arm; a circuit breaker connected in series with said prim coil; and a controlling coil connected w1t said auxiliary coil and adapted automatically to operate said circuit breaker for opening said primary coil circuit by the increased current through said auxiliary .coil when said secondary coil circuit is opened.

In testimony whereof I have signed my name to this specification.

- JOSEPH G. SOLA.

iliary coil; and means adapted automatically to open said primary coil circuit by the action of the increased current through said auxiliary coil when said secondary coil circuit is opened.

6. In an arrangement of the type described, the combination of a core bar, a primary coil on said core bar, other core'means providing an all-metal return path for the magnetic v flux through said core'bar, a secondary coil on said core, a core arm extending between said two coils comprising a shunt connection 7 ,from said core bar to said other core means and including an air gap therein adapted when the secondary coil circuit is closed to divert from the secondary coil a substantial part of the flux threading theprimary coil, an auxiliary coil on said core in secondary I relationship to said primary coil, circuit means including a switch connected with said primary coil, and means in operative relationship with said auxiliary coil adapted automatically to open said switch upon the change in the strength of the current through said auxiliary coil produced by the opening of the secondary coil circuit.

- 7. In an arrangement of the type described,

the combination of core means'comprising two core bars in spaced relation to each other,

cross-bars joining the ends of said first named bars, and a core arm including an air gap JOIIllIlg said first named bars at an intermediate point; a primary coil on one of said first named bars at one side of said core arm a secondary coil and an auxiliary coil in end to end relation with said primary coil and on the same core bar with saidprimary coil but at the opposite side of said core arm; and

means in operative relation with said auxiliary coil adapted automatically to open said primary coil circuit by reason of the increase in the strength of the current through said auxiliary coil when said secondary coil circuit is opened. g

8. In an arrangement of the type described, the combination of core means comprising two core bars in spaced relation to each other, cross-bars joining the ends of said first named bars, and a core arm including an air gap joining said-first named bars at an intermedlatepoint; a primary coil on one of said first named bars at one side of said core arm; a 

